Zink wants to take the printer off your desk and put it in your pocket. The question now is whether you want it there.

The Waltham, Mass.-based start-up has created--with help from Polaroid--a way to print photographs or documents without ink or an ink cartridge. Without an ink cartridge, a printer can be reduced to the size of an iPod or smaller, said CEO Wendy Caswell. The controlling factor when it comes to printer size is whether you want 2 x 3 inch prints or 4 x 6 inch prints. Zink says it has two manufacturing partners lined up, and products based on its technology will come out later this year.

The Zink system "can be embedded in any device," she said. It is also more environmentally friendly, the company says. Ninety-five percent of ink cartridges never get recycled.

The first two products will likely be a standalone printer and a camera with a built-in printer. The company is showing off the technology this week at the technology conference Demo '07 in Palm Desert, Calif. (Sonny Bono and Gerald Ford territory).

The trick is the paper. In conventional printers, print heads squirt ink in a meticulous pattern onto a sheet of paper, and the ink gets affixed through heat or other means.

In Zink's system, images are created when a heated printer head comes into contact with a sheet of specialized paper. The paper--which is actually a polymer but feels like ordinary photo paper--contains three crystalline layers. The layers are clear until heated. When heated, the material de-crystallizes and changes colors: One of the crystalline layers turns yellow, the middle one goes magenta and the final one turns blue. Images are created through a mosaic of magenta, yellow and blue pixels activated in the various layers.

The layers are activated at varying temperatures and require different cooking times. To create a yellow pixel, for instance, the printer head has to be at the highest temperature, but only has to touch the paper for a brief period, explained CTO Steve Herchen. Blue requires low temperature but a long contact time. Thus, when the printer head comes in contact with the paper, only one color is created for a particular pixel.

When the paper cools, the material doesn't revert to its crystalline state, but remains amorphous. Thus, the color pixels remain. (Shifting a base material between a crystalline and amorphous state is the basic idea behind ovonics and phase change memory). The paper is also recyclable.

Printers using Zink's system are similar to other products on the market, but do differ slightly. Canon, among others, makes portable color printers that can handle different photo paper sizes. These printers, however, have ink cartridges. Pentax, meanwhile, has come out with an inkless printer, but it only does grayscale.

The first printers using Zink's technology will only produce 2 x 3 inch photographs, but other sizes may be produced in the future. The target price is $99 for the standalone printer and $199 for the camera printer. Paper for the Zink items will run around $19.95 for a pack of 100 sheets. Besides working with camera and hardware manufacturers, Zink is trying to land deals with paper producers.

Products that require specialized paper--such as some of the first electronic pens--have had a checkered history. CEO Caswell counters, however, that buying specialized paper should be no more difficult than finding the particular cartridge to refill your printer.